The present invention relates to power MOSFETS, and in particular, to current sensing circuits for use with power MOSFETS which enable the current through the power MOSFET to be sensed in both the linear and saturated regions of MOSFET operation.
At the present time it is known to provide current sense structures for power MOSFETs which sense the drain-source current through the power MOSFET when the power MOSFET is in the saturated region, i.e., when the drain-source voltage is less than about 3 to 4 volts. When the drain source voltage is greater than 3 to 4 volts, the MOSFET is operating in the so-called linear region. Heretofore, current sense circuits have not been provided to sense the current when the power MOSFET operates in either the linear region or the saturated region.
It is an object of the present invention to provide a current sensing circuit for a power MOSFET which will sense the current in the power MOSFET in both the saturated and linear regions of operation.